There has been proposed a developing device of a laser printer in which a toner cartridge is detachably attached to a developing case, and opening/closing operations of a first blocking member that closes a first opening of the toner cartridge are interlocked with those of a second blocking member that closes a second opening of the developing case in order to prevent a toner from unnecessarily leaking.
JP-A-7-225514 discloses a developing device in which a case has a pair of right and left blankets, a second shutter is attached to an arm which is swingably disposed on boss portions of outer peripheries of support grooves of the blankets, and a first shutter is disposed on a lever which is swung about a support shaft of the toner cartridge. The support shaft of the toner cartridge is fitted into support grooves of the developing case. When the lever of the toner cartridge is swung in this state, an engaging projection disposed on the lever of the toner cartridge swings the arm of the developing case, thereby openingly/closingly swing the first shutter and the second shutter in an overlapping state.
In such a configuration, when the lever is accidentally swung in a state where the toner cartridge is detached from the developing case, the first shutter is swung to open a toner discharging port, thereby causing the possibility that a toner in the toner cartridge may leak. Also in the developing case which is in a state where the toner cartridge is detached, when the arm is accidentally swung, the second shutter is swung to open a toner introducing port. Thus, a toner may be leaked from a stirring chamber.
Thus, in the toner cartridge disclosed by JP-A-7-225514, when the toner cartridge is detached from the developing device, the first shutter is maintained to close the toner discharging port by a first locking mechanism. In the developing device, the second shutter is maintained to close the toner introducing port by a second locking mechanism. Therefore, if the toner cartridge is detached from the developing device, the first locking mechanism and the second locking mechanism prevent the first shutter and the second shutter from being accidentally swung to cause the toner to leak from the interior of the toner cartridge and the stirring chamber of the developing device.
However, each of the first locking mechanism and the second locking mechanism disclosed in JP-A-7-225514 is configured by a locking member and a screw. Further, the first locking mechanism and the second locking mechanism are configured separately from the first or second shutter. In order to respectively attach the locking mechanisms to the first shutter and the second shutter, a push pin and an engaging hole must be formed in each of the first shutter and the second shutter. Thus, structure of the toner cartridge and the developing case may be complicated.